Algebraic Multiplicity of an Eigenvalue

Click For Summary

Discussion Overview

The discussion centers around the algebraic multiplicity of an eigenvalue, specifically the relationship between algebraic and geometric multiplicities in the context of linear algebra proofs. Participants are exploring definitions, attempting proofs, and clarifying concepts related to eigenvalues and their multiplicities.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant is attempting to prove that the algebraic multiplicity of an eigenvalue λ is equal to dim null [T - λ I] dim V, seeking advice on how to proceed.
  • Another participant points out that the definition provided may refer to geometric multiplicity rather than algebraic multiplicity, noting that the two can differ.
  • A participant questions the accuracy of a statement regarding the relationship between the number of times λ appears on the diagonal of an upper triangular matrix and the dimensions mentioned, suggesting a potential error.
  • One participant clarifies that the geometric multiplicity of λ is the dimension of null [T - λ I], while the algebraic multiplicity is related to the exponent of λ in the factorization of A - cI.
  • Another participant expresses uncertainty about their proof attempt, indicating they feel stuck at the final stage.

Areas of Agreement / Disagreement

Participants express differing views on the definitions and relationships between algebraic and geometric multiplicities, indicating that multiple competing views remain. The discussion does not reach a consensus on the correctness of the statements made.

Contextual Notes

There are unresolved definitions and potential errors in the statements regarding multiplicities, as well as dependencies on the context of the proofs being attempted.

vish_maths
Messages
60
Reaction score
1
Please have a look at the attached images.I am attempting a proof for the statement : The algebraic multiplicity of an eigen value λ is equal to dim null [T - λ I] dim V.

Please advise me on how to move ahead. Apparently, I am at the final inference required for a proof but unable to move ahead. Thank you very much for your help in this regard.

Reference : To know how results (2) and (3) in the images come, you may please have a look at this ebook - pg 165, http://fetweb.ju.edu.jo/staff/EE/jrahhal/PDF/sc%20-%20Linear%20Algebra%20Done%20Right.pdf
 

Attachments

  • 1.png
    1.png
    55.1 KB · Views: 592
  • 2.png
    2.png
    42.7 KB · Views: 608
Last edited by a moderator:
Physics news on Phys.org
In my experience, the definition you gave is of the _geometric _ multiplicity, not the algebraic one. The two multiplicities may or may not coincide.
 
WWGD said:
In my experience, the definition you gave is of the _geometric _ multiplicity, not the algebraic one. The two multiplicities may or may not coincide.
Thank you for the answer. The notes which I have say that the number of times λ appears on the diagonal of an upper triangular matrix is equal to dim null [T - λ I] dim V. Do you think there is error in this statement as well?"

I have actually attempted the proof to prove this statement. Sorry about incorrectly saying it equal to algebraic multiplicity
 
Ah, sorry, I did not see the exponent dimV in your post , at first. In my experience, the geometric multiplicity of ## \lambda ## is the dimension of null## [T- \lambda I] ##. The algebraic multiplicity of ## \lambda ## is the multiplicity of the exponent of ##\lambda## in the factorization of ## A-cI ##.
 
Last edited:
No problem :) . Do you think I made a good attempt at the proof? I just think i got stuck in the last stage of the proof
 

Similar threads

Replies
8
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 4 ·
Replies
4
Views
5K
  • · Replies 7 ·
Replies
7
Views
4K
  • · Replies 9 ·
Replies
9
Views
4K